JP2012015448A - Flexible copper clad laminate and manufacturing method of the same, and circuit board using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flexible copper clad laminate formed by joining an electroless copper plating layer and polyimide resin, in which surface roughness of the polyimide resin is reduced to improve its surface smoothness and adhesive strength initially and after being heated is improved.SOLUTION: A flexible copper clad laminate has been invented by focusing on surface roughness of polyimide resin and concentration of alkali used in an electroless copper plating process. In the flexible copper clad laminate, the surface roughness of the polyimide resin is improved to reduce its surface smoothness and adhesive strength initially and after being heated is improved, by appropriately combining the surface roughness and the alkali concentration. Specifically, the flexible copper clad laminate is provided by, on the polyimide resin surface which has surface roughness caused by wet blasting of arithmetic mean roughness Ra of 0.05 μm or more and 1.0 μm or less and root mean square (RMS) roughness of 0.1 μm or more and 1.5 μm or less, forming an electroless copper plating layer from an electroless copper plating solution which has lower alkali level.

Description

  The present invention relates to a flexible copper clad laminate having a copper layer formed by electroless copper plating. More specifically, the present invention relates to a flexible copper-clad laminate in which a copper layer is formed on one side or both sides with sufficiently increased adhesion between a polyimide resin and an electroless copper plating layer.

  In recent years, various functions have been increasing in portable electronic devices and the like, and the necessity of incorporating many parts in a small container has been increasing rapidly. For this purpose, a flexible wiring board that can be finely bent and easily bent has been widely used for a printed circuit board on which components are mounted, and most of which uses a polyimide film.

  These flexible wiring boards are formed using a subtractive method that uses a flexible copper-clad laminate with a thick copper layer (for example, a thickness of 10 to 20 μm) and removes the copper layer unrelated to the wiring with an etching solution. However, there was a limit to miniaturization. Therefore, what has been attracting attention in recent years is the so-called semi-additive method, in which only the wiring part is electrically connected to the copper layer of a flexible copper-clad laminate consisting of an extremely thin copper layer (eg, about 1 μm thick). A thick copper layer is formed by copper plating to form a flexible wiring board. What is important in this method is an ultra-thin flexible copper-clad laminate, but there are electroless plating types and sputter types, and only the sputter type is currently on the market.

The sputter type is also called a dry plating method, in which an ultrathin layer (for example, several hundred angstroms to several thousand angstroms thick) is formed by sputtering, vapor deposition, etc., and then a thick film layer is formed by electrolytic copper plating. In some cases, electroless copper plating is performed before electrolytic copper plating. In this sputter type, when the copper layer is formed by sputtering or vapor deposition, the adhesion strength is weak to the base resin, especially the polyimide resin used in the flexible wiring board, so nickel, chromium, other metals, and those It was common to form a layer closely adhered to polyimide called a tough layer formed by sputtering or vapor deposition with the above alloy. However, if this tough layer is too thin, the adhesion strength after heating at 150 ° C. may be lowered.
Therefore, improvement measures have been made to increase the thickness of the tough layer to prevent a decrease in adhesion strength. However, if the tough layer becomes thicker in the subsequent process, the processing time becomes longer when the tough layer is removed, the entire copper wiring part is thinned, or the side etching phenomenon proceeds from the skirt part of the wiring part. The shortcoming occurred.

On the other hand, various methods of electroless plating have been disclosed, but most are related to electroless nickel plating. Electroless nickel plating generally has a method of co-depositing phosphorus or boron, and it has been pointed out that when these phosphorus and boron form an alloy with nickel, the hardness of the alloy layer increases, which has a great influence on flexibility. Yes. Further, since the nickel alloy layer needs to be removed, a side etching phenomenon occurs as in the sputtering method.
On the other hand, some electroless copper plating methods have also been proposed. The polyimide is opened by plasma treatment, ozone treatment, permanganic acid solution treatment or high-concentration alkali metal hydroxide solution treatment, etc. There are methods. However, these methods have not solved the disadvantage that the adhesion strength after heating decreases. Since these treatments cause the polyimide resin to become brittle excessively, even if the initial adhesive strength is high, the thermal treatment is considered to cause brittleness and reduce the adhesive strength.

On the other hand, Patent Document 1 improved the adhesion of electroless copper plating by wet blasting. Although the adhesion strength is ensured by appropriate roughening of the resin surface, the surface roughness tends to increase due to the large grain size of the abrasive grains. When the surface roughness is large, there is a problem that it is difficult to ensure the flatness of the copper surface after the copper plating process.
From the above results, the copper-clad laminate formed with the electroless copper plating layer that maintains the initial and post-heating adhesion using the electroless copper plating process that can be used in the production line has been put into practical use until now. There wasn't.

Japanese Patent No. 3250519

  Therefore, in a flexible copper clad laminate formed by directly bonding an electroless copper plating layer and a polyimide resin, the surface roughness of the polyimide resin is small, and the adhesion strength after heating at 150 ° C. for 240 hours at the initial stage is 0. It is an object of the present invention to provide a flexible copper clad laminate that can be maintained at 30 N / mm or more.

In the present invention, as a result of intensive studies in view of the above-described problems of the prior art, polygonal particles having a central particle diameter of 50% cumulative height by an electric resistance test method of 1.0 μm or more and less than 10 μm are added to a liquid. A first step of roughening the polyimide resin surface by wet blasting in which 35% by weight of the dispersed slurry is mixed with compressed air pressurized to 0.1 to 0.4 MPa and jetted at a high pressure;
A step of modifying to facilitate adsorption of catalyst particles on at least the surface of the polyimide resin, a step of applying catalyst particles to the modified surface, a step of activating the applied catalyst particles, and an activated catalyst And a step of depositing electroless copper plating on the particles,
Further, an electroless copper plating solution having an alkali metal hydroxide concentration of 2.5 g / L to 7.0 g / L as an alkali component, or an alkali metal hydroxide having a pH of 7.0 to 10.0. By forming a copper layer with an electroless copper plating solution not included,
It has been found that a flexible copper-clad laminate having a small surface roughness and ensuring initial and post-heating adhesion strength can be realized and can be practically used as a copper-clad laminate.

  In the present invention, the surface of the polyimide resin is physically roughened by a wet blast method, and after applying a metal catalyst thereon, the electroless copper plating layer is directly applied onto the polyimide resin with a low alkali electroless copper plating solution. By forming a copper layer by precipitation, it is not necessary to form a metal layer other than copper, the roughness of the polyimide surface is reduced, and sufficient initial and post-heat treatment adhesion strength can be obtained. A flexible copper-clad laminate is realized.

The basic process figure of this invention. Sectional drawing of the copper clad laminated board of this invention. Sectional drawing of the copper clad laminated board of this invention. Sample preparation process diagram for adhesion strength test.

  The present invention was made for the purpose of solving the problem that the adhesion between the polyimide resin and the electroless copper plating layer, which was a problem in the prior art, was weak, or the adhesion strength after heat treatment was weak. A flexible copper-clad laminate is manufactured by a process group including a step of roughening the surface of a polyimide resin substrate by a wet blast method and a step of forming a copper layer by electroless copper plating with low alkali. And

First, an embodiment of the present invention will be described in accordance with a basic process shown in FIG.
The main steps of the embodiment of the present invention are as follows: first, a polyimide film is prepared, the step of roughening the surface of the film, the step of modifying the surface of the roughened film, and the metal catalyst on the surface of the modified film , A step of activating the metal catalyst, a step of forming a metal layer by applying electroless copper plating using the activated metal catalyst as a core, and an electrolytic copper plating to be added as necessary To form a copper layer having a predetermined thickness. Conventionally, using an electroless copper plating process that can be used in a production line, it is difficult to manufacture a copper-clad laminate formed with an electroless copper plating layer that retains the initial and post-heating adhesion. In other words, sputtering has been used or copper plating has been performed on nickel plating. However, the present inventor uses the wet blast method disclosed in Patent Document 1 and uses it in a production line while making it possible to increase the flatness of the copper surface by reducing the roughness of the polyimide resin substrate surface. When electroless copper plating is performed by selecting a specific process and specific conditions in a process that can be performed, the electroless copper plating is directly formed on the polyimide resin. It has been found that a flexible copper clad laminate having a sufficiently high adhesion can be produced later. Such a flexible copper-clad laminate has long been desired, but has been thought to be difficult to put into practical use. The significance of the provision of this flexible copper-clad laminate by the present invention Is extremely large.
Next, each step will be described in order.

  First, a polyimide resin film is prepared. Thermosetting polyimide films marketed for flexible copper-clad laminates and flexible printed wiring boards, such as Kapton (registered trademark) manufactured by Toray DuPont, Apical (registered trademark) manufactured by Kaneka, Ube Industries Upilex (registered trademark) manufactured by Co., Ltd. can be used.

  Next, in the roughening step, the fine particles used for wet blasting include zirconia, alumina, silicon carbide and the like. In the present invention, Knoop hardness is 1300-2500 or Mohs hardness is 7-15. Therefore, polygonal particles having a center particle size of 1.0 μm or more and less than 10 μm at an accumulated height of 50% according to the electrical resistance test method are optimal. Polygonal particles having a Knoop hardness of 1300 to 2500 or a Mohs hardness of 7 to 15 and having a center particle size of 1.0 μm or more and 5 μm or less at a cumulative height of 50% according to the electrical resistance test method are more preferable.

If the hardness of the fine particles is low, there is a possibility that fine irregularities are less likely to occur due to repulsion of the treated surface when the fine particles are projected onto the surface to be treated. Moreover, since it will become weak generally when hardness is high, when a fine particle collides with a to-be-processed surface etc., there exists a possibility that it may crush and the effect of a roughening may fall.
The electrical resistance test method is a measurement method defined in JIS R6002; 1998.
If the particle size of the polygonal particles used for roughening is too small, the surface roughness of the polyimide resin may be insufficient and copper adhesion may be insufficient, while if too large, the surface roughness will be too large. Therefore, it may be difficult to ensure the flatness of the copper surface.

  Although there are various shapes of the fine particles, the present invention has an effect in that the corners of the fine particles collide with the surface to be processed, and the spherical particles have no effect. In the present invention, the term “polygonal particle” means a particle having a plurality of corners, and may be a spherical particle that is not intentionally formed, and may be a normal pulverized particle, but may be a rod-like particle. May be.

  A mixture of a slurry in which fine particles are dispersed in water or a suitable liquid in an amount of 1 to 35% by weight and compressed air pressurized to 0.1 to 0.4 MPa is jetted onto the surface of the resin base at high pressure. In particular, the slurry dispersed in an amount of 5 to 20% by weight may be mixed with compressed air pressurized to 0.25 to 0.35 MPa and injected at a high pressure. For other wet blasting processes used in the present invention, see Patent Document 1.

  In the present invention, by the wet blast treatment, the polyimide resin film has an arithmetic average roughness Ra of the surface roughness of 0.05 μm or more and 1.0 μm or less, and a mean square roughness RMS of 0.1 μm or more and 1.5 μm or less. A roughened surface is formed. The method for measuring the arithmetic average roughness Ra of the surface roughness is defined in JIS B0601; 2001, and the mean square roughness RMS is defined in JIS B0601; 1994. In particular, it is preferable to form a roughened surface having an arithmetic average roughness Ra of the surface roughness of 0.05 μm or more and 0.8 μm or less and a root mean square roughness RMS of 0.1 μm or more and 1.0 μm or less. If the surface roughness is too small, the adhesion of copper to the surface of the polyimide resin may be insufficient. On the other hand, if the surface roughness is too large, it may be difficult to ensure the flatness of the copper surface. .

  Furthermore, when small polygonal particles having a center particle size of 1.0 μm or more and 5 μm or less at a cumulative height of 50% according to the electrical resistance test method are used, the arithmetic average roughness Ra of the surface roughness is 0.05 μm or more and 0.00. It is possible to form a roughened surface having a relatively small roughness of 45 μm or less and a root mean square roughness RMS of 0.1 μm or more and 0.6 μm or less.

  Next is the surface modification process, which is generally called the conditioner process. The surface of the polyimide film is roughened using an alkaline or acidic liquid containing a surfactant. The surface charge is modified so that the palladium catalyst is easily attached. In general, the surface of the polyimide resin tends to be negatively charged, and the palladium catalyst is also negatively charged. Therefore, it is considered that the palladium catalyst is difficult to adsorb on the surface of the polyimide resin. Therefore, it is necessary to perform modification to charge the surface of the polyimide resin to a positive charge using a surfactant or the like.

In the present invention, at least one of a cationic system, an amphoteric system and a nonionic system may be used as the surfactant.
In the present invention, as in the prior art, the main purpose is to etch the surface of the polyimide film, such as hydrazine solution treatment, potassium permanganate solution treatment, alkali metal hydroxide solution treatment or strong acid solution treatment, or polyimide resin. There is no need for a chemical treatment process whose main purpose is to open the ring.

  Next is the catalyst application step, which is generally called the catalyst step. Typically, the surface of the polyimide film whose surface has been modified is deposited on the surface of the polyimide film without containing tin. It is immersed in a colloid catalyst-providing solution or a colloid catalyst-providing solution for depositing a palladium-tin complex, and the palladium complex or palladium-tin mixed complex is deposited on the polyimide resin surface.

  In addition, since this catalyst liquid deteriorates remarkably when moisture is mixed, generally a pre-dip process is performed as the immediately preceding process. As the pre-dip treatment solution, a solution having the same quality as that obtained by removing the metal component from the catalyst solution is usually used.

  Next, the activation process is generally called an accelerator process. Typically, it is immersed in an acidic or alkaline chemical solution to activate palladium, or tin removal and palladium activation. The palladium metal is adhered to the polyimide resin.

  Next, there is an electroless copper plating process, and there are a reduction type plating solution and a substitution type plating solution depending on the precipitation method. The substitution type plating solution may not be deposited on the surface of the polyimide film or may be peeled off immediately after deposition. In the present invention, a reduction type plating solution type is preferable.

  The configuration of the reducing plating solution is composed of a copper salt, a reducing agent, a pH adjuster, a buffer material, a complexing agent, a stabilizer, and the like. The copper salt is generally copper sulfate, but other copper salts may be used. As the reducing agent, formaldehyde, hydrazine and its compound, hypophosphite, dimethylamine borane (DMAB), Rochelle salt and the like are used, but hydrazine is toxic and is not used. Formaldehyde or hypophosphite is often used. Sodium hydroxide or aqueous ammonia is often used as the pH adjuster. The complexing agent is also called a chelating agent, and citric acid, ethylenediaminetetraacetic acid (EDTA), triethanolamine and the like are used. Other drugs are added as necessary.

Regarding the alkali component in the electroless copper plating, according to Japanese Patent No. 3208410, the blending amount of the alkali metal hydroxide is about 10 to 80 g / L, and if it is less than 10 g / L, the electroless copper plating film is formed. It is said that it is insufficient. As a result of examining the matching with the roughening treatment and the pretreatment for plating, the present inventors have stabilized the adhesion by reducing the alkali amount of the electroless copper plating solution and prevented the deterioration of the adhesion after the heating test. And found a way to withstand practical use.
That is, in the present invention, an electroless copper plating solution having an alkali metal hydroxide concentration of 2.5 g / L to 7.0 g / L as an alkali component, or an alkali having a pH of 7.0 to 10.0. It has been found that it is appropriate to use an electroless copper plating solution containing no metal hydroxide. If the alkali metal hydroxide concentration is outside the above range, even if there is adhesion immediately after the plating treatment, the adhesion will be significantly reduced after the heating test, or the adhesion will be significantly reduced immediately after the plating treatment. There is. The alkali metal hydroxide is an alkali metal hydroxide such as sodium, potassium, or lithium, and sodium hydroxide is particularly preferable. Similarly, if the pH is outside this range, even if there is adhesion immediately after the plating treatment, the adhesion may be significantly reduced after the heating test, or the adhesion may be significantly reduced immediately after the plating treatment. An electroless copper plating solution having an alkali metal hydroxide concentration of 3.0 g / L to 6.0 g / L, or 4.0 g / L to 5.5 g / L, or a pH of 7.5 to 9. An electroless copper plating solution containing no alkali metal hydroxide, which is 5, is more preferred.

More specifically, for example, in an electroless copper plating solution using formaldehyde as a reducing agent, as a result of investigation, an alkali metal hydroxide concentration of 2.5 g / L to 7.0 g / L is appropriate. I found it. The pH of the plating solution at this time is 11 or more and less than 12.5.
The copper concentration, which is another composition of the electroless copper plating solution, is preferably 2.5 g / L to 5.0 g / L, and the formaldehyde concentration is preferably 2.5 g / L to 7.0 g / L.

  In particular, an alkali metal hydroxide concentration of 4.0 g / L to 5.5 g / L, a copper concentration of 3.0 g / L to 4.0 g / L, and a formaldehyde concentration of 3.0 g / L to 5.0 g / L are desirable.

  In addition, electroless copper plating solutions that do not use formaldehyde as a reducing agent are both substituted and substituted, and many do not use an alkali metal hydroxide such as sodium hydroxide as the alkali component. In that case, it is controlled by pH instead of alkali amount. For example, in a plating solution using hypophosphite as a reducing agent, the pH is appropriately 7.0 to 10.0. In particular, the pH is preferably 7.5 to 9.5.

  The polyimide resin film to which the activated catalyst is attached is immersed in an electroless copper plating solution having the above composition to obtain a copper layer having a plating thickness of 0.1 to 5 μm on one or both sides of the palladium catalyst of polyimide. In particular, the plating thickness is preferably 0.2 to 1.0 μm.

  In this invention, you may complete a flexible copper clad laminated board only with the copper layer formed by the electroless copper plating with the said plating thickness of 0.1-5 micrometers. However, a copper layer is formed on the electroless copper plating layer by the second electroless copper plating layer or the electrolytic copper plating layer or a plurality of these layers, and has an arbitrary thickness of 0.1 to 25 μm. A flexible copper clad laminate can be formed. In the latter case, it is preferable that the total thickness of one or more electroless copper plating layers is 0.1 to 5 μm, particularly 0.2 to 1.0 μm, and the rest is an electrolytic plating layer.

  The flexible copper-clad laminate of the present invention is characterized in that since the surface roughness of the polyimide resin is low, a flat copper layer surface can be obtained even if the copper layer is thin. For example, when the thickness of the copper layer is 10 μm or more, a metallic luster can be obtained on the surface of the copper layer.

Electroless copper plating and electrolytic copper plating generate gases such as hydrogen during plating deposition, but these gases may be adsorbed in the deposited copper plating metal layer, and the gas, especially hydrogen gas, does not absorb metal. It is well known that the adhesion of plating may be deteriorated due to embrittlement (referred to as hydrogen embrittlement). In that case, in order to remove the adsorbed hydrogen gas, it is known that a heat treatment called annealing is performed after electroless copper plating and / or after electrolytic copper plating. It was. In the present invention, it has been found that heating conditions satisfying the following two formulas are appropriate when the heating temperature is T (° C.) and the heating time is t (hours) in an inert gas such as air or nitrogen.
7 × 10 ⁶ <T ³ × t <18 × 10 ⁶
60 ℃ ≦ T ≦ 180 ℃

  According to the above process according to the present invention, in a flexible copper clad laminate formed by directly bonding an electroless copper plating layer and a polyimide resin, the surface roughness of the polyimide resin is 0.05 to 1.0 μm. And a flexible copper clad laminate capable of maintaining the adhesion strength at the initial stage and after heating at 150 ° C. for 240 hours at 0.30 N / mm or more. The adhesion strength is preferably 0.35 N / mm or more, and more preferably 0.40 N / mm or more. The upper limit is not limited, but adhesion strengths of at least 1.20 N / mm, and even up to 1.40 N / mm can be realized.

  By using the flexible copper-clad laminate of the present invention, pattern wiring can be formed by a subtractive method or a semi-additive method, thereby creating a flexible wiring board.

  In the description of the present embodiment, the polyimide resin film has been described. However, the present invention is not limited to the film, and it goes without saying that the present invention is applicable to other forms of polyimide resin.

  In the embodiment of the present invention, a flexible copper-plated layer in which an electroless copper plating solution that does not intentionally add dissimilar metals such as nickel is formed using an electroless copper plating solution that does not intentionally eutect dissimilar metals. The laminated plate was explained, but an electroless copper plating solution containing a different metal such as nickel was used to form an electroless copper plating layer in which a different metal such as nickel was co-deposited in a small amount of 5% or less by weight. A flexible copper-clad laminate may be used.

Example 1
In this example, a polyimide film Kapton (registered trademark) 100EN (film thickness: 25 μm) manufactured by Toray DuPont Co., Ltd., which is generally used for flexible copper clad laminates, is used.

  Next, regarding roughening, polygonal particles of alumina material (Mohs hardness 12, Knoop hardness 2200) are used as fine particles used for wet blasting. Abrasive grains having a center grain size of 9.5 μm were selected.

  Using a small piece blasting machine manufactured by Macau Corporation, a mixture of 5% by weight of alumina particles dispersed in water and compressed air pressurized to 0.3 MPa was uniformly distributed over the entire surface of the polyimide film. High-pressure jetting.

  Next, surface modification, conditioner solution manufactured by Okuno Pharmaceutical Co., Ltd .: polyimide roughened by wet blasting with an alkaline chemical solution containing a surfactant mixed with OPC-B42 condition clean solution in water The surface is modified so that the palladium catalyst is easily attached.

  Next, for catalyst application, first, as a pre-dip step, after immersing in an OPC-SAL M agent manufactured by Okuno Seiyaku Kogyo Co., Ltd. in water, a catalyst manufactured by Okuno Pharmaceutical Co., Ltd .: OPC-80 Catalyzer Using a solution obtained by mixing List M solution and OPC-SAL M agent in water, the surface is modified by immersing it in a chlorine-based catalyst providing solution for depositing a tin-palladium complex on the surface of the polyimide film. Palladium and tin are deposited.

  Next, it is activation. Accelerator manufactured by Okuno Pharmaceutical Co., Ltd .: OPC-500 Accelerator MX-1 solution is mixed with water and immersed in an acidic chemical solution to activate palladium, remove tin, and remove palladium. Is adhered to the polyimide resin.

Next, although it is an electroless copper plating solution, electroless copper plating is performed using a reduced (also referred to as self-catalyst) electroless copper plating solution under the following composition and conditions. In addition to the following composition, additives such as a buffer, a complexing agent, and a stabilizer may be added as necessary.
Copper salt 3.5g / L
Formaldehyde (reducing agent) 4.0 g / L
Sodium hydroxide (alkalinity) 5.0 g / L
Temperature 25 ° C
Time 10 minutes A flexible copper clad laminate having a copper plating thickness of 0.3 to 0.5 μm was obtained under the above conditions.

  Next, for a confirmation test of the effect, a pattern for an adhesion strength test is formed by a semi-additive method on the flexible copper-clad laminate on which the electroless copper plating layer produced by the above process is formed. The process will be described with reference to FIG.

  First, a photoresist film is attached to the surface of the copper layer of the flexible copper-clad laminate. The resist film is exposed to light through a photomask on which a pattern for adhesion test is drawn. The resist film is treated with a developing solution to form a pattern on the resist. Copper is laminated to a thickness of 20 μm by electrolytic copper plating on the surface of the copper layer exposed in the cavity of the resist film (in the present invention, the adhesion strength is measured by the following method with the thickness of the copper layer being 20 μm). After removing the resist film with a stripping solution, the thin copper layer is removed with a copper etchant.

  The completed test sample was stored in air at 120 ° C. for 5 hours and subjected to heat treatment.

  The size of the test sample was formed in accordance with JIS C 6471 with a film width of 10 mm, a copper layer width of 3 mm, and a length of 10 cm.

  The adhesion strength was measured based on JIS C 6471 by attaching a sample to the outer periphery of a wheel having a diameter of 15 cm and measuring it with a small measuring instrument EZTest manufactured by Shimadzu Corporation under the conditions of an angle of 90 ° and a tensile speed of 50 mm / min. Moreover, the measured value was converted into N / mm.

  The adhesion strength was measured by comparing the “initial value” measured after the preparation of the sample with “after heating” measured at room temperature after being stored in an oven at 150 ° C. for 240 hours.

The surface roughness is VK85550 manufactured by Keyence Co., Ltd., and the measurement conditions are a lens magnification of 50 times, RUNMODE is color ultradeep, DISTANCE is 16 μm, PITCH is 0.02 μm, and measurement range is 298.3 μm × 223. Measured at 7 μm.
The evaluation results are shown in Table 1.

Example 2
In another example 2, polygonal particles of alumina material were used as fine particles used for wet blasting, and abrasive grains having a center particle size of 3.0 μm were selected.
Others are the same as in the first embodiment. The evaluation results are shown in Table 1.

Comparative Example 1
In Comparative Example 1, alumina fine particles were used as fine particles used for wet blasting, and abrasive grains having a center particle size of 14.0 μm were selected.
Others are the same as in the first embodiment. The evaluation results are shown in Table 1.

  According to JIS C 6471, the initial value is 0.5 N / mm or more, and when US UL Standard 796 is used, 0.35 N / mm or more is necessary after heating, but the surface roughness is reduced as shown in Table 1. However, the adhesion strength is maintained appropriately and is practically sufficient.

Example 3
In another example 3, polygonal particles of alumina material were used as fine particles used for wet blasting, and abrasive grains having a center particle size of 8.0 μm were selected.

Moreover, the following is used for the composition of the plating solution used for electroless copper plating.
Copper salt 3.5g / L
Formaldehyde (reducing agent) 4.0 g / L
Sodium hydroxide (alkalinity) 5.0 g / L
Temperature 25 ° C
Time 10 minutes Others are the same as in Example 1.

Example 4
In another Example 4, the composition of the plating solution used for electroless copper plating is as follows.
Copper salt 3.5g / L
Formaldehyde (reducing agent) 4.0 g / L
Sodium hydroxide (alkalinity) 3.0g / L
Temperature 25 ° C
Time 10 minutes Others are the same as in Example 3.

Comparative Example 2
In another comparative example 2, the composition of the plating solution used for electroless copper plating is as follows.
Copper salt 3.5g / L
Formaldehyde (reducing agent) 4.0 g / L
Sodium hydroxide (alkalinity) 10.0 g / L
Temperature 25 ° C
Time 10 minutes Others are the same as in Example 3.

Comparative Example 3
In another comparative example 3, the following composition is used for the plating solution used for electroless copper plating.
Copper salt 3.5g / L
Formaldehyde (reducing agent) 4.0 g / L
Sodium hydroxide (alkalinity) 2.0g / L
Temperature 25 ° C
Time 10 minutes Others are the same as in Example 3.

The adhesion strength was measured based on JIS C 6471 by attaching a sample to the outer periphery of a wheel having a diameter of 15 cm and measuring it with a small measuring instrument EZTest manufactured by Shimadzu Corporation under the conditions of an angle of 90 ° and a tensile speed of 50 mm / min. Moreover, the measured value was converted into N / mm.
The adhesion strength was measured by comparing the “initial value” measured after the preparation of the sample with “after heating” measured at room temperature after being stored in an oven at 150 ° C. for 240 hours.
The results are shown in Table 2.

  As shown in Table 2, when the alkalinity is high, the adhesion strength after heating is extremely lowered. However, when the alkalinity is lowered, the adhesion strength is appropriately maintained and is sufficient for practical use.

Example 5
In this example, a polyimide film Kapton (registered trademark) 100EN (film thickness: 25 μm) manufactured by Toray DuPont Co., Ltd., which is generally used for flexible copper clad laminates, is used.

  Next, regarding roughening, polygonal particles of alumina material (Mohs hardness 12, Knoop hardness 2200) are used as fine particles used for wet blasting. Abrasive grains having a center grain size of 8.0 μm were selected.

Using a roll type blasting machine manufactured by Macau Corporation, a mixture of 5% by weight of alumina particles dispersed in water and compressed air pressurized to 0.3 MPa was uniformly applied to both sides of the polyimide film. High pressure spray.
Others are the same as in the first embodiment.

  Based on JIS C 6471, a test sample was prepared by forming a pattern with a film width of 10 mm, a copper layer width of 3 mm, and a length of 10 cm on one surface and removing the copper layer on the other surface entirely.

Example 6
Based on JIS C 6471, a test sample was prepared by forming a pattern with a film width of 10 mm, a copper layer width of 3 mm, and a length of 10 cm on one surface, and leaving the copper layer on the other surface on the entire surface.
Others are the same as in the fifth embodiment.

The adhesion strength was measured based on JIS C 6471 by attaching a sample to the outer periphery of a wheel having a diameter of 15 cm and measuring it with a small measuring instrument EZTest manufactured by Shimadzu Corporation under the conditions of an angle of 90 ° and a tensile speed of 50 mm / min. Moreover, the measured value was converted into N / mm.
The adhesion strength was measured by comparing the “initial value” measured after the preparation of the sample with “after heating” measured at room temperature after being stored in an oven at 150 ° C. for 240 hours.
The results are shown in Table 3.

  As shown in Table 3, the same adhesion strength as that obtained by roughening one side of the one roughened on both sides is maintained.

Example 7
In Example 7, a plating solution using hypophosphite as a reducing agent is used.
First, polyimide film Kapton (registered trademark) 100EN (film thickness: 25 μm) manufactured by Toray DuPont Co., Ltd., which is generally used for flexible copper clad laminates, is used.

  Next, regarding roughening, polygonal particles of alumina material (Mohs hardness 12, Knoop hardness 2200) are used as fine particles used for wet blasting. Abrasive grains having a center grain size of 8.0 μm were selected.

  Using a single piece type small blasting machine manufactured by Macau Co., Ltd., a mixture of 5% by weight of alumina particles dispersed in water and compressed air pressurized to 0.3 MPa was applied to the entire polyimide film surface. High pressure spray uniformly.

  Next, with surface modification, a palladium catalyst adheres to the polyimide surface roughened by wet blasting with an alkaline chemical solution containing a surfactant mixed with conditioner MF312 liquid made by Nippon McDermid Co., Ltd. in water. Modify to make it easier.

  Next, as catalyst provision, first, as a pre-dipping process, after immersing in a solution obtained by mixing MF331L agent manufactured by Nippon McDermid Co., Ltd. in water, the catalyst MF350 solution manufactured by Nippon McDermid Co., Ltd., MF331L agent and hydrochloric acid are used in water. In the surface of the surface-modified polyimide film, the surface of the polyimide film is immersed in a chlorine-based catalyst providing solution for depositing a tin-palladium complex, and palladium and tin are deposited on the resin surface.

  Next, it is activated, Nikkakumidamido Co., Ltd. Accelerator MF370A liquid and MF370B liquid mixed in water, soaked in an alkaline chemical solution, activated palladium, tin was removed and palladium was adhered to the polyimide resin Let

Next, although it is an electroless copper plating liquid, electroless copper plating is carried out on the following conditions using Nippon Macder Mid Co., Ltd. MF390 liquid group. As the composition of the plating solution, an additive (such as a complexing agent) is added to the copper salt and the reducing agent.
pH 8.5
Temperature 75 ° C
5 minutes

Under the above conditions, the copper plating thickness is as thin as 0.1 to 0.2 μm. Therefore, after electroless plating, electrolytic plating is performed using the above plating solution, and the copper plating thickness is 0.3 to 0.4 μm. I got a plate.
Temperature 75 ° C
Current density 1A / dm ²
2 minutes

  Next, for a confirmation test of the effect, a pattern for an adhesion strength test is formed by a semi-additive method on the flexible copper-clad laminate on which the electroless copper plating layer produced by the above process is formed. The process will be described with reference to FIG.

  First, a photoresist film is attached to the surface of the copper layer of the flexible copper-clad laminate. The resist film is exposed to light through a photomask on which a pattern for adhesion test is drawn. The resist film is treated with a developing solution to form a pattern on the resist. Copper is laminated to a thickness of 20 μm on the copper layer surface exposed in the cavity of the resist film by electrolytic copper plating. After removing the resist film with a stripping solution, the thin copper layer is removed with a copper etchant.

  The completed test sample was stored in air at 120 ° C. for 5 hours and subjected to heat treatment.

  The size of the test sample was formed in accordance with JIS C 6471 with a film width of 10 mm, a copper layer width of 3 mm, and a length of 10 cm.

  The adhesion strength was measured based on JIS C 6471 by attaching a sample to the outer periphery of a wheel having a diameter of 15 cm and measuring it with a small measuring instrument EZTest manufactured by Shimadzu Corporation under the conditions of an angle of 90 ° and a tensile speed of 50 mm / min. Moreover, the measured value was converted into N / mm.

The adhesion strength was measured by comparing the “initial value” measured after the preparation of the sample with “after heating” measured at room temperature after being stored in an oven at 150 ° C. for 240 hours.
The results are shown in Table 4.

Example 8
In another example 8, polygonal particles of alumina material were used as fine particles used for wet blasting, and abrasive grains having a center particle size of 3.0 μm were selected.
Others are the same as in Example 7.
The results are shown in Table 4.

  As shown in Table 4, even a plating solution using hypophosphite as the reducing agent was able to obtain sufficient adhesion strength.

1a, 1b Polyimide resin substrate 2a, 2b, 2c Electroless copper plating layer 3a, 3b, 3c Electrolytic copper plating layer

Claims (8)

  In a flexible copper clad laminate in which a copper layer is directly bonded to one or both sides of a polyimide resin without an adhesive layer, the arithmetic average roughness of the surface roughness of at least the surface of the polyimide resin bonded to the copper layer Ra is 0.05 μm or more and 1.0 μm or less, the root mean square RMS is 0.1 μm or more and 1.5 μm or less, the copper layer is an electroless copper plating layer, and the polyimide resin of the copper layer A flexible copper-clad laminate having an adhesion strength after heating at 150 ° C. for 240 hours to 0.30 N / mm or more.   The flexible copper clad laminate according to claim 1, wherein the copper layer is formed of an electroless copper plating layer having a thickness of 0.1 μm to 5 μm.   The copper layer is formed of an electroless copper plating layer, and a thickness of 0 is formed on the electroless copper plating layer by a second electroless copper plating layer, an electrolytic copper plating layer, or a combination of a plurality of these layers. The flexible copper-clad laminate according to claim 1, wherein the flexible copper-clad laminate is formed of a copper layer having a thickness of 1 μm to 25 μm. A) A slurry in which one or both surfaces of a polyimide resin are dispersed in a liquid with polygonal particles having a central particle size of 1.0 to 10 μm at a cumulative height of 50% according to an electrical resistance test method in a liquid. Is processed by a wet blast treatment in which high pressure injection is performed by mixing with compressed air pressurized to 0.1 to 0.4 MPa, and the arithmetic average roughness Ra is 0.05 μm or more and 1.0 μm or less, and the mean square A first step in which the roughness RMS is a surface roughness of 0.1 μm or more and 1.5 μm or less;
B) A step of modifying the surface of the roughened polyimide resin to facilitate adsorption of catalyst particles, a step of imparting catalyst particles to the modified surface, and a step of activating the imparted catalyst particles And a step of depositing electroless copper plating on the activated catalyst particles using an electroless copper plating solution, and the concentration of alkali metal hydroxide as an alkali component is 2.5 g / L to 7. Using an electroless copper plating solution of 0 g / L or an electroless copper plating solution not containing an alkali metal hydroxide having a pH of 7.0 to 10.0, electroless copper plating is applied to the polyimide resin surface. Including a second stage of performing,
The manufacturing method of the flexible copper clad laminated board characterized by the adhesive strength after the heating of 150 degreeC 240 hours with respect to the polyimide resin of the obtained copper layer being 0.30 N / mm or more.   The method for producing a flexible copper-clad laminate according to claim 4, wherein after the electroless copper plating, the obtained electroless copper plating layer is subjected to heat treatment.   The method for producing a flexible copper-clad laminate according to claim 4 or 5, wherein the alkali metal hydroxide is sodium hydroxide.   A thickness of 0.1 μm or more and 25 μm by a second electroless copper plating layer, an electrolytic copper plating layer or a combination of a plurality of layers on the electroless copper plating layer according to claim 4. The method for producing a flexible copper-clad laminate according to claim 4, wherein the copper layer is formed by the following copper layer, and heat treatment is performed after one or a plurality of copper plating treatments.   The flexible wiring board which performed pattern wiring formation by the subtractive construction method or the semiadditive construction method using the flexible copper clad laminated board of Claims 1 thru | or 3.

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